Electronic device including pin hole array mask above optical image sensor and laterally adjacent light source and related methods

ABSTRACT

An electronic device may include an optical image sensor and a pin hole array mask layer above the optical image sensor. The electronic device may also include a display layer above the pin hole array mask layer that includes spaced apart display pixels, and at least one light source laterally adjacent the optical image sensor and capable of directing light into a user&#39;s finger when adjacent the optical image sensor.

TECHNICAL FIELD

The present invention relates to the field of electronics, and, more particularly, to the field of optical image sensors.

BACKGROUND

Fingerprint sensing and matching is a reliable and widely used technique for personal identification or verification. In particular, a common approach to fingerprint identification involves scanning a sample fingerprint or an image thereof and storing the image and/or unique characteristics of the fingerprint image. The characteristics of a sample fingerprint may be compared to information for reference fingerprints already in a database to determine proper identification of a person, such as for verification purposes.

A fingerprint sensor may be particularly advantageous for verification and/or authentication in an electronic device, and more particularly, a portable device, for example. Such a fingerprint sensor may be carried by the housing of a portable electronic device, for example, and may be sized to sense a fingerprint from a single-finger.

Where a fingerprint sensor is integrated into an electronic device or host device, for example, as noted above, it may be desirable to more quickly perform authentication, particularly while performing another task or an application on the electronic device. In other words, in some instances it may be undesirable to have a user perform an authentication in a separate authentication step, for example switching between tasks to perform the authentication.

SUMMARY

An electronic device may include an optical image sensor and a pin hole array mask layer above the optical image sensor. The electronic device may also include a display layer above the pin hole array mask layer that includes a plurality of spaced apart display pixels, and at least one light source laterally adjacent the optical image sensor and capable of directing light into a user's finger when adjacent the optical image sensor.

The electronic device may also include a transparent cover layer above the display layer defining a finger placement surface capable of receiving a user's finger adjacent thereto. The at least one light source may be laterally adjacent the transparent cover layer so that light from the at least one light source is directed into the user's finger when adjacent the transparent cover layer, for example.

The pin hole array mask layer may have at least one light opening therein. The at least one light source may be positioned below the pin hole array mask layer and aligned with the at least one light opening, for example.

The electronic device may further include a device housing carrying the optical image sensor, the pin hole array mask layer, the display layer, and the at least one light source. The at least one light source may include a plurality of light sources carried adjacent a periphery of the device housing, for example.

The at least one light source may include at least one of a visible light source, an infrared light source, and an ultraviolet light source, for example. The optical image sensor, pin hole array mask layer, and finger placement surface may be configured to define overlapping areas at the finger placement surface, and spaced apart areas at the optical image sensor.

The electronic device may also include a flexible circuit substrate carrying the optical image sensor. The electronic device may further include an optically transparent body between the optical image sensor and the pin hole array mask layer, for example.

The electronic device may include an optically clear adhesive layer above the optical image sensor. The optical image sensor may be capable of performing at least one of an authentication function, a spoof detection function, and a vital sign measurement function, for example.

A method aspect is directed to a method of making an electronic device. The method may include positioning a pin hole array mask layer above an optical image sensor, and positioning a display layer above the pin hole array mask layer. The display layer includes a plurality of spaced apart display pixels. The method may also include positioning at least one light source laterally adjacent the optical image sensor and capable of directing light into a user's finger when adjacent the optical image sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an electronic device according to an embodiment.

FIG. 2 is a schematic block diagram of an electronic device of FIG. 1.

FIG. 3 is a schematic cross-sectional view of a portion of the electronic device of FIG. 1.

FIGS. 4a and 4b are graphs comparing light and integration line numbers relative to a frame according to rolling shutter techniques.

FIG. 5 is a graph comparing light to integration line number relative to a frame according to a global shutter mode.

FIGS. 6a and 6b are graphs of estimated image and object plane resolution respectively for the optical image sensor of the electronic device of FIG. 1.

FIGS. 7a and 7b are graphs of estimated imaging resolution in terms of point-spread function shape for the optical image sensor of the electronic device of FIG. 1.

FIGS. 8a-8g are simulated images illustrating resolution of the optical image sensor for a given diameter of an opening in the pin hole array mask layer of the electronic device of FIG. 2.

FIG. 9 is a schematic cross-sectional view of a prototype electronic device for generating images according to the optical image sensing principles of the electronic device of FIG. 1.

FIGS. 10a-10h are images captured using the prototype electronic device of FIG. 9 illustrating image resolution.

FIGS. 11a-11h are simulated images using the prototype electronic device of FIG. 9 illustrating image resolution.

FIGS. 12a-12c are examples of separate sub-images of overlapping object areas from the prototype electronic device of FIG. 9.

FIGS. 13a-13b are captured images illustrating restoral of a single image from overlapping sub-images from the prototype electronic device of FIG. 9.

FIG. 14 is a captured image at a relatively low angle using a front illuminated prototype device.

FIGS. 15a-15d are captured images using different colored light with the front illuminated prototype device.

FIGS. 16a-16c are captured images at a relatively high angle using the front illuminated prototype device.

FIGS. 17a-17c are captured images at a relatively high angle using the front illuminated prototype device.

FIGS. 18a-18c are captured images at a relatively high angle using the front illuminated prototype device.

FIG. 19 is a schematic cross-sectional view of a portion of an electronic device according to another embodiment of the present invention.

FIG. 20 is a schematic cross-sectional view of a portion of an electronic device according to another embodiment of the present invention.

FIG. 21 is an enlarged schematic cross-sectional view of a portion of an electronic device according to another embodiment of the present invention.

FIG. 22 is an enlarged schematic cross-sectional view of a portion of an electronic device according to another embodiment of the present invention.

FIG. 23 is a schematic block diagram of a finger biometric sensor according to an embodiment.

FIG. 24a is a diagram illustrating direct reflectance as it applies to the finger biometric sensor of FIG. 23.

FIG. 24b is a diagram illustrating diffuse reflectance and local remittance as it applies to the finger biometric sensor of FIG. 23.

FIG. 24c is a diagram illustrating scattering-transmission as it applies to the finger biometric sensor of FIG. 23.

FIG. 24d is a diagram illustrating total internal reflection as it applies to the finger biometric sensor of FIG. 23.

FIGS. 25a and 25b are schematic diagrams illustrating the fingerprint ridge three-dimensional (3D) data generation concept.

FIG. 26 is a schematic diagram of a portion of a finger biometric sensor illustrating overlapping target areas according to an embodiment.

FIG. 27 is a schematic diagram of a portion of a finger biometric sensor for determining the 3D structure of the fingerprint pattern of the user's finger according to an embodiment.

FIGS. 28a and 28b are schematic diagrams illustrating specular reflection for a light source at two different illumination directions and angles according to an embodiment.

FIG. 29 is a diagram illustrating diffuse reflection and remission with respect to multiple image sensors with overlapping target areas according to an embodiment.

FIG. 30 is a schematic diagram of a portion of a finger biometric sensor in accordance with an embodiment.

FIG. 31a is a finger image taken using blue light at an angle of 60° in accordance with an embodiment.

FIG. 31b is an image profile graph at 60° in accordance with an embodiment.

FIG. 32a is a finger image taken using blue light at an angle of 20° in accordance with an embodiment.

FIG. 32b is an image profile graph at 20° in accordance with an embodiment.

FIGS. 33a and 33b are 3D plots of diffuse and specular finger image areas illustrating horizontal profiles for all incident profiles according to an embodiment.

FIG. 34 is a more detailed schematic diagram of the finger biometric sensor within an electronic device according to another embodiment.

FIG. 35 is a schematic block diagram of an electronic device in accordance with an embodiment.

FIG. 36 is a more detailed schematic cross-sectional view of the electronic device of FIG. 35.

FIG. 37 is a schematic cross-sectional view of an electronic device in accordance with an embodiment.

FIG. 38 is a schematic top view of an electronic device according to an embodiment.

DETAILED DESCRIPTION

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout, and prime notation and numbers in increments of 100 are used to refer to like elements in different embodiments.

Referring initially to FIGS. 1 and 2, an electronic device 1020 illustratively includes a housing, for example, a portable housing 1021, and a processor 1022 carried by the portable housing. The electronic device 1020 is illustratively a mobile wireless communications device, for example, a cellular telephone. The electronic device 1020 may be another type of electronic device, for example, a tablet computer, laptop computer, wearable computer, etc.

A display 1023 is also carried by the portable housing 1021 and is coupled to the processor 1022. The display 1023 may be a light emitting diode (LED) display, for example, and may have additional circuitry to provide touch display features, as will be appreciated by those skilled in the art. Further details of the display 1023 are described below.

A wireless transceiver 1025 is also carried within the housing 1021 and coupled to the processor 1022. The wireless transceiver 1025 cooperates with the processor 1022 to perform at least one wireless communications function, for example, for voice and/or data. In some embodiments, the electronic device 1020 may not include a wireless transceiver 1025 or other wireless communications circuitry.

A memory 1026 is also coupled to the processor 1022. The memory 1026 is for storing finger matching biometric template data, for example. The memory 1026 may store other or additional types of data.

As will be appreciated by those skilled in the art, if the display 1023 is in the form of a touch display, the touch display may operate as both an input device and a display. As such, the display 1023 would cooperate with the processor 1022 to perform one or more device functions in response to input. For example, a device function may include a powering on or off of the electronic device 1020, initiating communication via the wireless transceiver 1025, and/or performing a menu function based upon input to the touch display.

The processor 1022 may change the display 1023 to show a menu of available applications based upon pressing or input to the touch display. Of course, other device functions may be performed based upon input to the touch display 1023. Other or additional finger-operated user input devices may be carried by the portable housing 1021, for example, a pushbutton switch 1024, which may alternatively or additionally be used for device functions as will be appreciated by those skilled in the art.

Referring now additionally to FIG. 3, an optical image sensor 1031 for sensing a biometric of a user, such as, for example, an image of the fingerprint patterns of the user's finger 1040, is carried by the housing 1021 under the display 1023. More particularly, the optical image sensor 1031 includes an integrated circuit (IC) substrate, and image sensing circuitry carried by the IC substrate. The optical image sensor 1031 may be coupled to a circuit substrate, for example, a flexible substrate 1034 by way of a grid array having ball grid array (BGA) contacts 1035 or other coupling technique. The optical image sensor 1031 may be a back-illuminated sensor or backside illumination (BSI) image sensor as will be appreciated by those skilled in the art.

The electronic device 1020 optionally includes a light source 1041. The light source 1041 may be one or more light emitting diodes (LEDs) and/or may be part of the display layer 1036. In other words, the display pixels 1038 may be the light source or there may be a separate or additional light source. The light source 1041 directs light into the user's finger 1040, and may direct light for the optical image sensor 1031. For example, different LEDs of the display may allow dynamic changing of and/or more flexibility with respect to the wavelengths of the light and the angle of illumination. A visible light source or invisible light source (e.g., infrared (IR) or ultraviolet (UV)), and/or another type of light source may be used, or a combination of light sources may be used. However, IR light may penetrate deeper within a user's finger 1040, compared to other colors of light, for example, blue-colored light.

It may be desirable that the light source 1041 be synchronized with the optical image sensor 1031, and more particularly, signal acquisition of the optical image sensor. For example, the light source 1041 may cooperate with the optical image sensor 1031 so that the optical image sensor operates in one or both of a rolling shutter mode and a global shutter mode, as will be appreciated by those skilled in the art. The global shutter mode may improve tolerance to background light or interference and reduce power consumption as will be appreciated by those skilled in the art. Additionally, the optical image sensor 1031 may cooperate with a filter, for example, a narrow band spectral filter, that may correspond to the spectra of the light source 1041. The filter may reduce background effects on finger recognition or increase tolerance to the background. The filter may be an optical filter, for example.

Further details of the rolling shutter and global shutter modes will now be described. A typical optical image sensor generally operates in a rolling shutter mode. In this mode, the integration time starts and ends at different times for each sensor line. Such operation may be inefficient when combined with active illumination, as it generally requires illumination to be turned in one of two regimes.

Referring now to the graph in FIG. 4a , in a first regime, illumination, i.e., the light source 1041, is on from the start of the first line integration to the end of the last line integration. This regime has two disadvantages: 1) the integration time is shorter than the illumination on time, causing illumination power inefficiency; and 2) if the illumination switch is between the consecutive frames, such as to change the angle or wavelength, the next frame start is delayed until the first frame ends, adding a wait time no shorter than the readout time, causing a time inefficiency.

Referring now to the graph in FIG. 4b , in a second regime, the illumination is on from the start of the last line integration to end of the first line integration. This regime has two disadvantages: 1) the integration time is longer than the illumination on time, causing background light interference inefficiency; and 2) the illumination duty cycle is relatively short causing a high peak power operation.

Referring now to the graph in FIG. 5, it may be thus desirable to operate the optical image sensor 1031 in a global shutter mode. In this mode the integration time starts and ends at the same time for all sensor lines. Such operation has three advantages: 1) The illumination on time is equal to the integration time causing efficient use of the illumination power; 2) there is typically no need to have dead time between the frames in case of illumination switching such as to change angle or wavelength; and 3) the illumination duty cycle is maximum relaxing the need for high peak power operation.

An optically clear adhesive layer (OCA) 1042 is above the optical image sensor 1031, and more particularly, carried by an upper surface of the optical image sensor. An optically transparent body or support member 1043 spaces the OCA layer 1042 from a pin hole array mask layer 1050. In other words, the support member 1043 is between the OCA layer 1042 and the pin hole array mask layer 1050.

The pin hole array mask layer 1050 is above the optical image sensor 1031, for example, spaced from the optical image sensor by a distance in a range of 100-300 microns. More particularly, the pin hole array mask layer 1050 is illustratively carried on a top surface of the support member 1043. The pin hole array mask layer 1050 is an opaque mask and has a plurality of openings 1051 or pin holes therein to permit the passage of light therethrough. The openings 1051 may be uniformly spaced or spaced in a honeycomb pattern, for example. The pitch of spacing of the openings 1051 may be, for example, in a range of 1-3 mm and more particularly, about 1.5 mm. The spacing between the openings 1051 or pitch affects image resolution. Additionally, each opening 1051 may have a size in the range of 5-40 microns, for example. Of course, the size of each opening 1051 or pin hole affects the sensed images from the optical image sensor 1031, as will be described in further detail below. The pin hole array mask layer 1050 is opaque, and thus does not permit light to pass through. The pin hole array mask layer 1050 may include chromium, for example, a layer of chromium, to provide the opacity. Of course, other materials, whether in a layer or not, may be used to provide opacity.

A display layer 1036, which is part of the display 1023, is above the pin hole array mask layer 1050. The display layer 1036 illustratively includes an array of display pixels 1038 and/or micro-lenses for displaying images, as will be appreciated by those skilled in the art. In particular, the display layer 1036 may be part of a light-emitting diode (LED) display. The LEDs or display pixels 1038 may be spaced apart to allow light to pass through, and may be aligned with the openings 1051 or pin holes.

A display encapsulation layer 1044 is over the display layer 1036. Another optically clear adhesive layer 1045 is over the display encapsulation layer 1044. A transparent cover layer 1046, for example, that includes onyx, is above the display layer 1036 and defines a finger placement surface that is capable of receiving the user's finger adjacent thereto. More particularly, the transparent cover layer 1046 is carried by the optically clear adhesive layer 1045, and an upper surface of the transparent cover layer 1046 defines the finger placement surface 1047 for receiving the user's finger 1040. The finger placement surface 1047 may be spaced from the pin hole array mask layer 1050 by a distance in a range of 1.5 mm-2 mm (i.e., 1500-2000 microns), for example. Of course, the finger placement surface 1047 may be spaced from the pin hole array mask layer 1050 by another distance, for example, based upon desired image characteristics.

In an exemplary electronic device 1020 that includes the optical image sensor 1031, the height of the layers may be as follows: the flexible substrate 1039 may be about 0.15 mm thick, the optical image sensor 1031 may be about 0.1 mm, the optically clear adhesive layer 1042 may be about 0.05 mm, the support member 1043 may be about 0.2 mm, the display encapsulation layer 1044 may be about 0.1 mm, the second optically clear adhesive layer 1045 may be about 0.15 mm, and the transparent cover layer 1046 about 1.5 mm. Of course, the spacing between and size of each layer may be different, but as will be described below it may be desirable that the spacing between the optical image sensor 1031 and the pin hole array mask layer 1050 be relatively small.

The relative spacing and geometry of the optical image sensor 1031, the pin hole array mask layer 1050, and the finger placement surface 1047 define overlapping areas at the finger placement surface, and spaced apart areas at the optical image sensor. Accordingly, the spacing between the pin hole array mask layer 1050 and the optical image sensor 1031 determines an amount of sensed image overlap, i.e., at the finger placement surface 1047. A larger spacing corresponds to a larger amount of image overlap which may be undesirable for processing. In other words, the more overlap, the more computationally intense image construction may be. In contrast, a smaller distance between the optical image sensor 1031 and the pin hole array layer 1050 may result in no significant overlap, and thus, images may be more easily reconstructed.

The optical image sensor 1031, and more particularly, the image sensing circuitry senses a user's finger 1040 or an object placed adjacent the finger placement surface 1047, and based thereon, may perform one or more biometric functions, for example, user authentication (a matching operation), a biometric enrollment function, and/or a spoof detection function. Moreover, when the display 1023 is in the form of a touch display, when the user contacts the touch display, for example, during a navigation function or other touch display input, data from the user's finger 1040 is sensed or acquired by the optical image sensor 1031, for example, for finger matching and/or spoof detection, as will be appreciated by those skilled in the art.

Operation of the electronic device 1020 as it pertains to finger biometric sensing using the optical image sensor 1031 will now be described. Light from the light source 1041 and/or display pixels 1038 is scattered based upon an object, for example, the user's finger 1040, adjacent the finger placement surface 1047 or on the transparent cover layer 1046. The scattered light is captured by the optical image sensor 1031 through the pin holes and/or micro-lenses in the display layer 1036 and the openings 1051 or pin holes in the pin hole array mask layer 1050.

Advantageously, the display layer 1036 is a multi-spectral and multi-shadow illuminator and generally not affected by ambient light. Moreover, in some embodiments, the display layer 1036 may be used for spoof detection, for example, impedance based spoof detection and/or other light-based or electric field-based detection techniques, as will be appreciated by those skilled in the art.

Even still further, the die of the optical image sensor 1031 has a relatively large amount of non-utilized areas, which can be allocated for other processing, for example, finger biometric or fingerprint processing and/or spoof detection, e.g. a spectrometer.

Using a pin hole array mask layer 1050 as part of an imaging technique produces separate images of overlapping object areas. Shading and magnification of the image may be adjusted by adjusting different parameters with respect to size and distance from object pin hole array layer 1050 and to the optical image sensor 1031. For example, a magnification of 0.114 can be achieved based upon the height and the average refractive index ratio. Opening or pin hole image shading is given by a cos⁴ function. Shading allows for separation of the sensed images, even though there are overlapping areas. The shading determines the effective size of the object area images by a single opening 1051 or pin hole.

With respect to resolution, the use of the pin hole array layer 1050 allows image resolution of about 15 microns. Thus, a relatively wide range of pixel sizes may be used. For example, an object plane resolution of about 120 microns may be achieved.

More particularly, the pin hole optical system resolution may be determined based upon a pin hole imaging point spread function (PSF) that is a convolution of geometrical and diffraction PSF. Both are axially symmetric 2D functions. The geometrical PSF quantifies blurring due to the finite size of each opening or pin hole. The geometrical PSF is given by the pin hole circle projections onto the optical image sensor 1031 (for image space resolution) or onto the object (for object space resolution). The diffraction PSF quantifies the additional blurring due to the light diffraction off small openings, for example, for a circular aperture, it is given by the first Bessel function.

With respect to image overlap, using a signal level in the range of 64%-100%, a field-of-view angle of ±26.5° may be obtained. When used with an opening 1051 or pin hole size of 200 microns, an object area size of 1750 microns, and a spacing or pitch of the openings of 1500 microns, the object may be full covered by the imaged areas. By using a signal level in the range of 20%-100%, a field-of-view angle of ±48° may be obtained. When used with an opening 1051 or pin hole size of 200 microns, an object area size of 1750 microns, and a pin hole spacing or pitch of the openings of 1500 microns, each object area is sensed or imaged multiple times from different angles in the same capture. The overlap information may be used to improve resolution and signal-to-noise ratio (SNR), and/or extract 3D information, for example.

Referring to FIGS. 6a and 6b , the graphs 1060 a and 1060 b are graphs of opening 1051 or pin hole size based upon an object-to-opening distance of 1750 microns and an optical image sensor-to-opening distance of 200 microns. The graphs 1060 a, 1060 b plot the diameter of each opening 1051 in microns against the image plane resolution (FIG. 6a ) and the object plane resolution (FIG. 6b ) in microns, respectively. Lines 1061 a, 1061 b correspond to light having a wavelength of 380 nm, lines 1062 a, 1062 b correspond to light having a wavelength of 460 nm, lines 1063 a, 1063 b correspond to light having a wavelength of 525 nm, lines 1064 a, 1064 b correspond to light having a wavelength of 630 nm, lines 1065 a, 1065 b correspond to light having a wavelength of 850 nm, and lines 1066 a, 1066 b correspond to light having a wavelength of 940 nm. The size of the openings 1051 that may be particularly well suited for visible light is 9 microns.

Additionally, the lines' PSF width rise at relatively large pin holes or openings 1051 is the geometric resolution-dominant regime. The fast PSF width rise at relatively smaller openings 1051 is the diffraction-dominant regime. The two effects combined produce what may be considered an optimum pin hole size for the best resolution. It may be desirable that the selection of the openings 1051 size be somewhat above the optimum determined resolution, for example, to trade-off resolution for signal-to-noise ratio (SNR).

Referring now to the graphs 1070 a, 1070 b in FIGS. 7a and 7b , pin hole imaging resolution is illustrated. The graph 1070 a in FIG. 7a corresponds an opening 1051 or pin hole size of 9 microns, an object-to-opening distance of 1750 microns, and an image sensor-to-opening distance of 200 microns, while the graph 1070 b in FIG. 7b corresponds to an opening or pin hole size of 15 microns, an object-to-opening distance of 1750 microns and an image sensor-to-opening distance of 200 microns. Lines 1071 a, 1071 b correspond to light having a wavelength of 460 nm, lines 1072 a, 1072 b correspond to light having a wavelength of 525 nm, lines 1073 a, 1073 b correspond to light having a wavelength of 630 nm, and lines 1074 a, 1074 b correspond to light having a wavelength of 850 nm. Illustratively, for an opening 1051 or pin hole diameter of 9 microns, the object plane resolution (1/e) is 105 microns, while for an opening 1051 or pin hole diameter of 15 microns, the object plane resolution (1/e) is 155 microns. The graph 1070 a corresponds to a relatively small pin hole size, a diffraction regime, has a bell shape, and thus, a relatively significant wavelength dependence. The graph 1070 b corresponds to a relatively large pin hole size, a mostly geometrical regime, has a square shape, and thus negligible wavelength dependence.

It is also desirable to account for pixel blurring. The pixel PSF is a convolution of pixelization and crosstalk PSF. The pixelization PSF is due to the finite size of the pixel, and it can be modeled by a 2D-square sinc function or by integrating a super-sampled image. The crosstalk PSF is the pixel property that is measured, for example, by way of angle and wavelength. The crosstalk PSF depends on the incoming angle, and more particularly, on pixel position with respect to the image center.

The crosstalk PSF typically is of the order of one pixel in size, but can have a long-range tail, especially for near infrared (NIR) light, for example. Pixel blurring, however, is not generally expected to be relatively significant compared to optical blurring since the pixel size is significantly smaller than the size of the openings 1051 or pin holes.

Referring now to FIGS. 8a-8g , simulated images illustrating exemplary resolutions are illustrated. The images are for green light, an opening 1051 diameter of 15 microns, and a resolution of 155 microns. FIG. 8A illustrates 4 lines per millimeter with a line width of 125 microns. FIG. 8B illustrates 5 lines per millimeter with a line width of 100 microns. FIG. 8C illustrates 6 lines per millimeter with a line width of 83 microns. FIG. 8D illustrates 7 lines per millimeter with a line width of 71 microns. FIG. 8E illustrates 8 lines per millimeter with a line width of 63 microns. FIG. 8F illustrates 9 lines per millimeter with a line width of 56 microns, and FIG. 8G illustrates 10 lines per millimeter with a line width of 50 microns. A 1/e resolution of 155 microns advantageously allows for resolving of up to about 7 lines per millimeter, which may depend on a contrast degradation limit, for example.

With respect to shading, shading includes both optical shading and pixel shading. Optical shading can be approximated by the “cosine-4^(th)” geometrical factor. Light is received at the optical image sensor 1031 at angles that depends on the refractive index ratio of the pin hole plane. The pixel shading is measured and is expected to be no more than an extra cosine factor in addition to the geometrical effect.

With respect to signal-to-noise ratio (SNR) and integration time, the size of each opening 1051 or pin hole drives the resolution-SNR trade off. The signal level is based upon pin hole plane irradiance, opening 1051 or pin hole size, pixel sensitivity, integration time, and shading.

The noise level for a given optical image sensor may be a function of the signal with constant parameters including pixel properties, such as for example, read noise, photo response non-uniformity (PRNU), and fixed pattern noise (FPN). For example, for a resolution-optimal opening diameter of 9 microns, the F-number is 22.2. For an opening diameter of 15 microns, with a sensor distance of 200 microns, the F-number is 13.3 (a resolution loss of about 1.5×, and an integration time reduction for the same SNR of about 2.8×). As will be appreciated by those skilled in the art, the image center signal is given by: Signal=luminance[cd/m²]*π*reflectivity*transmissivity/(4F ²)*sensitivity[e/lx−s]*tau[s]

For a typical display luminance of about 520 cd/m², reflectivity of about 70%, F/13.3, pixel pitch 6 microns, integration time of 100 ms, the resultant signal may be about 140e, with an SNR of about 11. This SNR may be considered relatively low, and thus it may be desirable for the image modulation to be about 10% for a workable contrast. A larger effective pixel pitch, i.e., spacing between pixels, for example via binning, may be considered for an SNR increase or an integration time decrease.

With respect to image distortion, image distortion may result based upon a fisheye or inverse-fisheye effect. The image distortion may be due to the difference in the refractive index between the object interface media and the optical image sensor 1031, for example, and is modeled by the sine ratio refraction function. Pin hole imaging itself does not introduce significant distortion, thus maintaining the angle tangents relatively constant. Distortion may be reduced by using materials having a closer match, for example nearly the same refractive index. Distortion may be corrected by image processing before stitching together individual images, as will be appreciated by those skilled in the art.

Referring now to FIG. 9, a prototype electronic device 1200 was used to generate images according to the principles described above. More particularly, a chromium mask 1201 having a thickness of about 12 microns carried by a back glass 1202 having a refractive index of 1.5 and a thickness of 1500 microns was used to simulate an object to be sensed. The chromium mask 1201 simulating the object was a Thorlabs R2L2S1P positive resolution target having a 2-inch by 2-inch size, a soda lime glass substrate (back glass) and a chromium pattern.

A diffused light source 1203 was positioned above the chromium mask 1201. The diffused light source 1203 included multiple blue light-emitting diodes (LEDs) uniformly illuminating a diffuser over 2 inches. The central wavelength was about 450 nm. The light source 1203 was limited to blue LEDs because of a residual transmission of chromium masks at higher wavelengths that caused reduced contrast.

The chromium mask 1201 was spaced from a pin hole array mask layer 1204 by about 1500 microns as the pin hole array mask layer was also carried by a back glass 1205 having a refractive index of about 1.5 and a thickness of about 1500 microns. The pin hole array mask layer 1204 had a thickness of about 12 microns, and the diameter of the single opening 1206 in the pin hole array mask layer was 12 microns.

An optical image sensor 1207 was below the pin hole array mask layer 1204 and spaced therefrom by about 750 microns with an associated refractive index of about 1.3. The 750 micron spacing included a 150 micron air gap 1208, a cover glass layer 1209 with a thickness of 300 microns and a refractive index of 1.5, and a second air gap 1210 having a thickness of 300 microns. The predicted object plane resolution was 38 microns (PSF—1/e diameter; equivalent to a minimum resolved line-pair width).

Referring additionally to the images in FIGS. 10A-10H and FIGS. 11A-11H, the prototype was used to generate images, which were compared to simulated images, respectively. FIGS. 10A-10H correspond to captured or generated images for 18, 16, 14, 12.5, 11, 10, 9, and 8 lines per millimeter, respectively. FIGS. 11A-11H correspond to the simulated images for 18, 16, 14, 12.5, 11, 10, 9, and 8 lines per millimeter, respectively. It should be noted that 18 lines per millimeter is still resolved, but as illustrated, the contrast is relatively low (line width of 28 microns). Referring particularly to FIGS. 10E-10H, the visible distortion is due to the “inverse fisheye” effect to the refraction index step on the pin hole or opening 1051.

Referring now to FIGS. 12A-12C, exemplary images of separate sub-images of overlapping object areas are illustrated. The captured images in these figures were taken from a 5×5 pin hole array layer having a 12 micron diameter with 1000 micron spacing. FIGS. 13A and 13B illustrate restoral of a single image from overlapping sub-images, for example, those illustrated in FIGS. 12A-12C.

Further tests were performed using a front illuminated prototype device that show that with respect to finger ridge imaging, contrast generally strongly depends on angle and wavelength. More particularly, with respect to a front illuminated prototype device the light source was positioned laterally adjacent the image sensor and was laterally adjusted for different angles of light. The same chromium mask as described with the prototype above was used to simulate an object to be sensed.

Referring now to the image in FIG. 14, the ridge image contrast at 550 nm is relatively low when the light source angle is close to normal, for example. Referring now to FIGS. 15A-15D, the contrast with blue light (450 nm, FIG. 15A) or green light (550 nm, FIG. 15B) is illustratively better than with red light (650 nm, FIG. 15C) or infrared light (940 nm, FIG. 15D). FIGS. 16A-16C are captured images at a relatively high angle at 550 nm, 850 nm, and 940 nm, respectively. FIGS. 17A-17C and FIGS. 18A-18C are additional captured images at the relatively high angle at 550 nm, 850 nm, and 940 nm, respectively. Illustratively, the contrast is significantly improved at high angles, but still lower at infrared wavelengths. The ridge density is about 3 lines per millimeter.

While the electronic device 1020 has been described herein as being in the form of a mobile wireless communications device, the electronic device may be in the form of a standalone optical image sensing device (i.e., a finger biometric sensing or fingerprint sensing device). Moreover, while the optical image sensor 1031 has been described primarily as being used for biometric authentication, it is understood that the optical image sensor, and more particularly, the image sensing circuitry, is capable of performing any or all of a biometric authentication function, spoof detection function, and a vital sign measurement function.

In particular, the sensed 3D geometry of shadowing using the pin hole array mask layer 1050, the multi-spectral nature of the imaging, and/or other characteristics of live fingers may be used for biometric authentication, for example. The optical image sensor 1031 may also be capable of performing sensing other biometric features, such as, for example, heart or pulse rate (which may be used for determining a blood pressure), and/or pulse or blood oximetry, and may be based upon the ability of the sense images at different wavelengths. As will be appreciated by those skilled in the art, for detecting a heart rate, a combination of green and IR light may be used, and for detecting a blood oxygen level, a combination of red and IR light may be used.

Still further, the optical image sensor 1031 may be used in combination with the openings 1051 to operate in an ambient light sensing mode, which may be relatively desirable in wearable electronic devices, for example. More particularly, by using, for example, the entire pin hole array mask layer 1050 and the entire pixel array of the optical image sensor 1031, a relatively high angle of light acceptance may result, which is generally desirable for ambient light sensing operations.

Further details of the operation of the ambient light sensing mode will now be described. All pixels may be combined into a single output, and read out with extremely low power consumption readout circuitry. The optical image sensor 1031 in combination with the pin hole array mask layer 1050 may then integrate light in very wide field of view (FOV), for example, up to 180 degrees. A typical camera, for example, senses light in a relatively narrow FOV, typically between 60 and 70 degrees, which may be too small for operation in an ambient light sensing mode. By having a very large, for example, up to 180 degree FOV for the pin hole array mask layer 1050 in combination with the optical image sensor 1031 may provide a relatively large advantage over a typical camera, for example.

The use of the pin hole array mask layer 1050, or even pinhole imaging techniques, provides wide-angle light sensing since the pinholes or openings 1051 are located relatively close to the optical image sensor 1031. The effective focal length is thus significantly lower than the size of the optical image sensor 1031. When the pixels are combined in a single output, it would be sensitive to nearly all the light entering the openings 1051. This allows a relatively low-power ambient light sensing mode that would have a stability advantage over typical sensors due to the reduced orientation dependence, for example.

Referring now to FIG. 19, a portion of an electronic device 1020′ illustrating an exemplary integration design. A substrate 1034′ is spaced from a base 1039′. The optical image sensor 1031′ is carried by an upper surface of the substrate 1034′ Passive components 1049′ are carried by a lower surface of the substrate 1034′. Bond wires 1057′ couple the optical image sensing circuitry to circuitry carried by the substrate 1034′. A transparent glass layer 1059′ is carried the enclosure, and has a thickness, for example, of 0.5 mm. An enclosure 1058′ extends upwardly from the substrate 1034′ around the optical image sensor 1031′. The enclosure 1058′ spaces the pin hole array mask layer 1050′ and the transparent glass layer 1059′ from the optical image sensor 1031′, for example, by a distance of 150 microns defining an air gap therebetween. A pin hole array mask layer 1050′ is carried by a lower surface of the transparent layer 1059′, for example, a glass layer. A light absorptive adhesive 1092′, for example, epoxy, may secure the transparent glass layer 1059′ and the pin hole array mask layer 1050′ to the enclosure 1058′.

Referring now to FIG. 20, the components or elements illustrated in FIG. 19 are integrated into an exemplary electronic device 1020′. A printed circuit board (PCB) 1081′ couples the substrate 1034′, and more particularly, the lower surface of the substrate adjacent the passive components 1049′. A display layer 1036′ including spaced apart display pixels 1038′ is carried by the upper surface of the substrate 1034′ laterally adjacent, or around, the enclosure 1058′. The display layer 1036′ may be coupled to display control circuitry 1082′ carried off the substrate 1034′. A transparent cover layer 1046′ is over the transparent layer 1059′. The transparent cover layer 1046′ may be secured to the transparent layer 1059′ with an adhesive, for example. The transparent cover layer 1046′ may be glass or onyx, for example, or may be another material.

A method aspect is directed to a method of making an electronic device 1020. The method includes positioning a pin hole array mask layer 1050 above an optical image sensor 1031, and positioning a display layer 1036 above the pin hole array mask layer. The display layer 1036 includes spaced apart display pixels 1038. The method also includes positioning a transparent cover layer 1046 above the display layer 1036 defining a finger placement surface 1047 capable of receiving a user's finger 1040 adjacent thereto.

Another method aspect is directed to a method of sensing an optical image. The method includes using an optical image sensor 1031 to sense light reflected from a user's finger 1040 adjacent a finger placement surface 1047 defined by a transparent cover layer 1046, through the transparent cover layer, through a pin hole array mask layer 1050 above the optical image sensor, and through a display layer 1036 above the pin hole array mask layer, wherein the display layer includes spaced apart display pixels 1038.

Referring now to FIG. 21, in another embodiment, the pin hole array mask layer 1050″ including the openings 1051″ may not be between the optical image sensor 1031″ and the display layer 1036″, but instead, carried by or integrated with the display layer. Illustratively, the display layer 1036″ includes an array of spaced apart display pixels 1038″ and/or micro-lenses for displaying images and which are spaced apart to allow light to pass through. The spacing between the display pixels 1038″, which allows the light to pass through, defines the openings 1051″. This is in contrast to embodiments where the space between the spaced apart display pixels 1038 may be aligned with the openings 1051 or pin holes in the pin hole array mask layer 1050. Method aspects are directed to a method of making a related electronic device and a method of using or sensing a finger using the electronic device.

Referring now to FIG. 22, in yet another embodiment, the pin hole array mask layer 1050′″ includes lenses 1091′″ in the openings 1051′″. Each of the lenses 1091′″ may have a diameter of about 40-100 microns, for example. The lenses 1091′″ may advantageously improve image quality and the SNR, which may thus reduce optical power for illumination and total overall power consumption, which may be particularly, advantageous when used with mobile or portable devices. Lenses may alternatively or additionally be included in the display layer 1036′″.

Referring now to FIG. 23, a finger biometric sensor 1130 which may be carried by the electronic device 1020 described above, for example, illustratively includes a dielectric layer 1146. The dielectric layer 1146 may be a transparent cover layer, for example, as also described above. Other materials and/or layers may form the dielectric layer 1146. The dielectric layer 1146 has a front surface 1147 that receives the user's finger 1140 thereon and an opposing back surface 1148.

Light sources 1141 a-1141 n inject light into the user's finger 1140. The light sources 1141 a-1141 n may be selectively operable at different wavelengths, for example. At least some of the light sources 1141 a-1141 n are adjacent the back surface 1148 of the dielectric layer 1146. In some embodiments, there may be a single light source, which may be movable along the back surface of the dielectric layer 1146.

Image sensors 1131 a-1131 n, for example, in the form of pin hole cameras, are adjacent a back surface of the dielectric layer defining a plurality of overlapping target areas directed toward the user's finger 1140. The image sensors 1131 a-1131 m may each be in the form of an optical image sensor, such as, for example, the optical image sensor described above, and may be for sensing a finger biometric of a user, such as, for example, an image of the fingerprint patterns of the user's finger 1140.

It should be appreciated by those skilled in the art that several image sensors 1131 a-1131 n may be packaged in a single integrated circuit, and the image sensors may collectively be referred to an as an image sensor. The image sensors 1131 a-1131 n may be positioned relative to respective light sources 1141 to define respective specular reflection angles therebetween, as will be appreciated by those skilled in the art.

A controller 1122 or processor selectively operates the light sources 1141 and collects image data from the image sensors 1131 a-1131 n based upon diffuse scattering and specular reflections from the user's finger 1140, as will be explained in further detail below. The controller 1122 generates fingerprint ridge three-dimensional (3D) data, and more particularly, based upon the specular reflection angles, for example. The controller 1122 may also selectively operate the light sources 1141 a-1141 n in the different wavelengths. The controller 1122 may determine whether an object adjacent the dielectric layer 1146 and sensed by the image sensors 1131 a-1131 n, is a spoof based upon the different wavelength light, as will be appreciated by those skilled in the art.

Referring now additionally to FIGS. 24a-24d , examples of how the user's finger 1140 interacts with the dielectric layer 1146 or glass are illustrated. Interaction of the user's finger 1140 with light is based upon the positioning of the light sources 1141 a-1141 n and the image sensors 1131 a-1131 n. FIG. 24a illustrates direct reflectance where the light sources 1141 a, 1141 b generate light or illumination denoted by I, and the image sensors 1131 a, 1131 b receive light, denoted by R, are positioned so that they are both relatively close to each other, for example, and so that the angle between them is nearly vertical, which captures specular reflection. FIG. 24b illustrates diffuse reflectance and local remittance. The light sources 1141 a, 1141 b and the image sensors 1131 a, 1131 b are spaced apart at different angles such that the image sensors do not capture the specular reflection, but instead, the diffuse reflection, which is away from the specular reflection.

FIG. 24c illustrates scattering-transmission. The light source 1141 a is relatively far away from the image sensors 1131 a, 1131 b, which capture non-local remission. Another effect of interaction is ridge shadowing, where the light source is angled, with respect to the image sensor, but less than an angle for total internal refection (TIR). The image sensor is near vertical, but yet reduces or avoids specular reflection.

FIG. 24d illustrates TIR on the dielectric layer 1146. The angle of the light sources 1141 a, 1141 b is between the TIR of air and the TIR of skin of the finger 1140. The image sensors 1131 a, 1131 b may receive specular or diffuse reflection. Another interaction effect is fluorescence whereby the light source is ultraviolet (UV), and the image sensor receives longer wavelength light.

The sensing concept described herein is based upon illumination degrees of freedom. For example, the incoming angle of illumination may correspond to whether there is frustrated total internal reflection (FTIR), shadowing, and/or non-shadowing. The illumination degrees of freedom may also include a distance of the target of the illumination to the readout target distance. The sensing concept described herein is also based upon readout degrees of freedom. For example, the readout degrees of freedom may include specular diffusion, diffuse reflection, and remitted light. Other and/or additional light behaviors may be considered as part of either the illumination or readout degrees of freedom.

Referring now to FIGS. 25a and 25b , simplified diagrams illustrate the 3D fingerprint imaging concept. Multiple image sensors 1131 a, 1131 b or receivers may be used at different angles. A sequence of illumination sources 1141 a (FIG. 25a ), 1141 n (FIG. 25b ) are also used from different angles.

Referring now additionally to FIG. 26, a portion of a finger biometric sensor illustrating overlapping target areas is illustrated. Multiple cameras or image sensors 1131 a-1131 e are positioning under the dielectric layer 1146, which defines a finger platen or finger biometric sensing area, so that each region of the user's finger 1140 are visible in multiple camera views. For each spot on the surface of the user's finger 1140 there is intensity data available from several image sensors 1131 a-1131 e.

Referring now additionally to FIG. 27, to determine the 3D structure of the fingerprint pattern of the user's finger 1140, the controller 1122 cooperates with the image sensors 1131 a-1131 n to measure the slope of the skin surface across the ridge and valley pattern. If the angle of illumination is known, for example, the controller 1122 may determine the slope of any portion of the target by determining which image sensor at a given position sees the specular reflection 1189 from that particular region.

Referring now additionally to FIGS. 28a and 28b , the surface of the user's finger 1140 is generally not smooth and has texture. Hence, the specular reflection is generally not confined to a single sharply defined angle. Rather it covers a somewhat broader angle. This allows the image sensors to be spaced periodically below the user's finger 1140, yet still capture the specular reflection. Effects of changing the illumination direction and angle are illustrated with respect to specular reflection 1187. Illustratively, changing the illumination direction (see, for example 1141 a, 1141 n) and angle provides more information about the 3D structure.

Referring additionally to FIG. 29, diffuse reflection and remission 1188 are illustrated with respect to multiple image sensors 1131 a-1131 e with overlapping target areas. The image sensors 1131 a-1131 e are positioned so that they see the diffuse reflection and remission. Differences in intensity, which are captured by the image sensors 1131 a-1131 e are caused by the illumination striking the skin of the user's finger 1140 at different angles.

Areas where the illumination angle is near normal will appear brighter in the diffuse image, while areas where the illumination angle is far from normal (e.g., more grazing) will appear darker in the diffuse image. Changing the color of the illumination changes the amount of difference between high angle areas and low angle areas. Shorter wavelength light (e.g., blue) generally does not penetrate or remit as much. Longer wavelength light (e.g., red) penetrates, spreads, and remits in a larger area around its entry point. This washes out the differences between areas with different angles of illumination.

Referring now additionally to FIG. 30, raw data generated by the finger biometric sensor 1130 will now be described. In general, there exists an optical intensity measurement. For example, an optical intensity measurement exists for each spot on the surface of the user's finger 1140 (spot location (x,y)), for each light source 1141 a (source location(x,y), color(c)), and for each image sensor 1131 a-1131 d that sees or captures that spot (camera location(x,y)). The data may be collected and formed into an array to be processed by the controller 1122, for example, to extract one or more desired types of data.

In visible light images, diffuse scattering areas and specular reflection areas are observed. The specular reflection causes a higher contrast. Specular reflection area presence and position within the image depends on the pattern orientation with respect to the incoming angle azimuth, and specular reflection spatial phase depends strongly on the incoming angle incident. This dependence can be used to collect the ridge 3D structure information, since the phase depends on the second derivative of the profile.

Referring additionally to FIGS. 31a and 31b , an image and graph respectively illustrate finger image profiles at 60°. The normalized image example using blue light (FIG. 31a ) illustrates a specular reflection area along the top edge of the image and a diffuse scattering elsewhere. The graph in FIG. 31b illustrates the signal profile in the specular 1177 area shows relatively higher contrast relative to the diffuse 1178 area.

Referring additionally to FIGS. 32a and 32b , an image and graph respectively illustrate image profiles at 20°. The finger image, similar to the 60° profile, is based upon a blue light source. The location of the specular area shifts when the incident angle changes (FIG. 32a ). The profile phase within the specular 1176 area also shifts (the bright signal ridges in the image move laterally) (FIG. 32b ). The diffuse profile is denoted by 1175.

Referring now to FIGS. 33a and 33b , example image horizontal profiles for all incident profiles, i.e., at 0-90° are illustrated. FIG. 33a illustrates the specular profile, while FIG. 33b illustrates the diffuse profile. The specular image area profiles show a significant gradual shift of the imaged ridge. The diffuse image area profiles show almost no shift of the imaged ridge.

Referring now to FIG. 34, a schematic diagram of the finger biometric sensor within an electronic device is illustrated. More particularly, the finger biometric sensor 1130′ is embodied within a display. The display pixels 1138′ of the display, which are carried by a display substrate 1128′, are the light sources and provide the illumination. The reflected light passes through the openings 1151′ or pin holes between adjacent display pixels 1138′ and is captured by the image sensor 1131 a′.

It should be noted that only a single opening 1151′ and image sensor 1131 a′ are illustrated for ease of explanation. The light entering a pixel or the image sensor 1131 a′ may include light from sources causing direct specular reflection 1119′, sources causing diffuse and remissive reflection 1118′, and sources causing shadowing reflection 1117′.

Indeed, the collected image data may be used to generate fingerprint ridge 3D data, which may be used to generate a finger image. The generated finger image may be used by the controller 1122 for performing an authentication function, for example, by matching the generated data to stored enrolment data. The generated finger image data may also be used by the controller 1122 to determine a spoof, that it determine whether an object adjacent the finger biometric sensor is in fact a live finger or a fake finger, latent fingerprint, or other type of spoofed finger.

A method of generating fingerprint ridge three-dimensional (3D) data uses a finger biometric sensor 1130 that includes a dielectric layer 1146 having a front surface 1147 capable of receiving a user's finger 1140 thereon, at least one light source 1141 a-1141 n capable of injecting light into the user's finger, and image sensors 1131 a-1131 n adjacent a back surface 1148 of the dielectric layer defining a plurality of overlapping target areas directed toward the user's finger. The method includes using a controller 1122 to collect image data from the image sensors 1131 a-1131 n based upon diffuse scattering and specular reflections from the user's finger 1140, and generate fingerprint ridge 3D data.

Referring now to FIGS. 35 and 36, in another embodiment of an electronic device 1320, an optical image sensor 1331 for sensing a biometric of a user, such as, for example, an image of the fingerprint patterns of the user's finger 1340, is carried by the housing 1321 under the display 1323. Similar to embodiments described above, the optical image sensor 1331 includes an integrated circuit (IC) substrate, and image sensing circuitry carried by the IC substrate. The optical image sensor 1331 may be coupled to a circuit substrate, for example, a flexible substrate 1334 by way of a grid array having ball grid array (BGA) contacts or other coupling techniques. The optical image sensor 1331 may be a back-illuminated sensor or backside illumination (BSI) image sensor as will be appreciated by those skilled in the art. Of course, the image sensor 1331 may be a front-side illuminated (FSI) image sensor, or other type of sensor.

The electronic device 1320 optionally includes a light source 1341 laterally adjacent the optical image sensor 1331. The light source 1341 directs light into the user's finger 1340 when the user's finger is adjacent the optical image sensor, and may direct light for the optical image sensor 1331. The light source 1341 may be one or more light emitting diodes (LEDs) that are physically separated from or not part of the display layer 1336. In other words, the display pixels 1338 are distinct from the light source 1341. The light source 1341 may be a visible light source or invisible light source (e.g., infrared (IR) or ultraviolet (UV)), and/or another type of light source may be used, or a combination of light sources may be used. However, IR light may penetrate deeper within a user's finger 1340, compared to other colors of light, for example, blue-colored light. The light source 1341 may also be relatively bright, for example, about 1000 nits. In some embodiments, the light source 1341 may have an adjustable brightness, for example, adjustable based upon application, the user's finger, and/or the size of the pin holes. As described above, it may be desirable that the light source 1341 be synchronized with the optical image sensor 1331, and more particularly, signal acquisition of the optical image sensor.

Illustratively, an optically clear adhesive layer (OCA) 1342 is above the optical image sensor 1331, and more particularly, carried by an upper surface of the optical image sensor. The OCA layer 1342 may be a liquid optically clear adhesive layer, for example. Of course, the OCA layer 1342 may be another type of OCA layer.

An optically transparent body or support member 1343 spaces the OCA layer 1342 from a pin hole array mask layer 1350. In other words, the support member 1343 is between the OCA layer 1342 and the pin hole array mask layer 1350.

The pin hole array mask layer 1350 is above the optical image sensor 1331, for example, spaced from the optical image sensor by a distance in a range of 100-300 microns. More particularly, the pin hole array mask layer 1350 is illustratively carried on a top surface of the support member 1343. The pin hole array mask layer 1350 is an opaque mask and has a plurality of openings 1351 or pin holes therein to permit the passage of light therethrough. The openings 1351 may be uniformly spaced or spaced in a honeycomb pattern, for example. The pitch or spacing of the openings 1351 may be, for example, in a range of 1-3 mm and more particularly, about 1.5 mm. The pitch or spacing may be within another range, for example, less than 1 mm, and may be determined by geometry parameters of the stack, the targeted image resolution, and/or signal-to-noise ratio (SNR). As will be appreciated by those skilled in the art, the spacing between the openings 1351 or pitch affects image resolution. Additionally, each opening 1351 may have a size in the range of 5-40 microns, for example. Of course, the size of each opening 1351 or pin hole affects the sensed images from the optical image sensor 1331, as will be described in further detail below. The pin hole array mask layer 1350 is opaque, and thus does not permit light to pass through. The pin hole array mask layer 1350 may include chromium, for example, a layer of chromium, to provide the opacity. Of course, other materials, whether in a layer or not, may be used to provide opacity.

A display layer 1336, which is part of the display 1323, is above the pin hole array mask layer 1350. In some embodiments, the pin hole array mask layer 1350 may be part of the display 1323, for example, pin holes may be formed as part of the display layer 1336 using metal lines and/or a black material, as will be appreciated by those skilled in the art. The display layer 1336 illustratively includes an array of display pixels 1338 and/or micro-lenses for displaying images, as will be appreciated by those skilled in the art. In particular, the display layer 1336 may be part of a light-emitting diode (LED) display. The LEDs or display pixels 1338 may be spaced apart to allow light to pass through, and may be aligned with the openings 1351 or pin holes.

A display encapsulation layer 1344 is over the display layer 1336. Another optically clear adhesive layer 1345 is over the display encapsulation layer 1344. A transparent cover layer 1346, for example, that includes onyx, is above the display layer 1336 and defines a finger placement surface 1347 that is capable of receiving the user's finger adjacent thereto. The transparent cover layer 1346 may be another type of transparent material, for example, glass. More particularly, the transparent cover layer 1346 is carried by the optically clear adhesive layer 1345, and an upper surface of the transparent cover layer 1346 defines the finger placement surface 1347 for receiving the user's finger 1340. The finger placement surface 347 may be spaced from the pin hole array mask layer 1350 by a distance in a range of 1.5 mm-2 mm (i.e., 1500-2000 microns), for example. Of course, the finger placement surface 1347 may be spaced from the pin hole array mask layer 1350 by another distance, for example, based upon desired image characteristics. The relative dimensions of the different layers have been described above.

Illustratively, the light source 1341 is laterally adjacent the transparent cover layer 1346. The relative positioning of the light source 1341 laterally adjacent the transparent cover layer 1346 permits light from the light source to be directed into the user's finger 1340 when the user's finger is adjacent the transparent cover layer or the finger placement surface 1347.

The relative spacing and geometry of the optical image sensor 1331, the pin hole array mask layer 1350, and the finger placement surface 1347 define overlapping areas at the finger placement surface, and spaced apart areas at the optical image sensor. Accordingly, the spacing between the pin hole array mask layer 1350 and the optical image sensor 1331 determines an amount of sensed image overlap. A larger spacing corresponds to a larger amount of image overlap which may be undesirable for processing. In other words, the more overlap on the image sensor 1331, the more computationally intense image construction may be. In contrast, a smaller distance between the optical image sensor 1331 and the pin hole array layer 1350 may result in no significant image overlap on the image sensor, and thus, images may be more easily reconstructed.

The optical image sensor 1331, and more particularly, the image sensing circuitry senses a user's finger 1340 or an object placed adjacent the finger placement surface 1347, and based thereon, may perform one or more biometric functions, for example, user authentication (a matching operation), a biometric enrollment function, and/or a spoof detection function. Moreover, when the display 1323 is in the form of a touch display, when the user contacts the touch display, for example, during a navigation function or other touch display input, data from the user's finger 1340 is sensed or acquired by the optical image sensor 1331, for example, for finger matching and/or spoof detection, as will be appreciated by those skilled in the art.

A controller 1322 or processor selectively operates the light sources 1341 and cooperates with the optical image sensor 1331 to collect finger biometric data, for example. The controller 1322 may also selectively operate the light source 1341 in the different wavelengths and/or at different brightness. The controller 1322 may determine whether an object adjacent the transparent cover layer 1346 and sensed by the optical image sensor 1331, is authenticated, for example, by comparing the sensing biometric data with enrollment biometric data, a spoof based upon the different wavelength light, a vital sign measurement function, different angles of illumination, and/or different light polarization, as will be appreciated by those skilled in the art. Of course, other spoof detection techniques may be used.

While a controller 1322 has been described herein, it should be appreciated that the functions of the controller may be embodied in the optical image sensor 1331. In other words, the optical image sensor 1331 may perform all or some of the functions described herein with respect to the controller 1322 and a discrete controller may not be used. Of course, a separate or discrete controller 1322 and optical image sensor 1331 may be used.

Referring now to FIG. 37, in another embodiment, the light source 1341′ may not be laterally adjacent the transparent cover layer 1346′. Instead, the pin hole array mask layer 1350′ may have a corresponding light opening 1351′ therein. The light source 1341′ is positioned below the pin hole array mask layer 1350′ and is aligned with the light source. The light source 1341′ may be carried with the optical image sensor 1331′ by the flexible substrate 1334′. The light source 1341′ may not be carried by the same substrate as the optical image sensor 1331′ and the substrate may not be flexible.

Referring now to FIG. 38, in another embodiment, the electronic device 1320″ may include multiple light sources 1341″ for example, in the form of LEDs spaced around a periphery of the device housing 1321″. In some embodiments, the light sources 1341″ may be integrally formed within the device housing 1321″. The controller 1322″ may selectively operate certain light sources 1341″, for example, based upon the application or function, and/or based upon the optical image sensor 1331″.

As will be appreciated by those skilled in the art, illumination may be considered a relatively important factor in the operation of the optical image sensor 1331. While optical fingerprint sensing behind the display layer 1336 can be done using the pin hole imaging technique described herein whereby illumination can be provided by the display itself, the illumination may not be powerful or bright enough to obtain an acceptable signal-to-noise ratio (SNR). Additionally, controlling illumination of the display layer 1336 may be relatively complicated, for example for finger biometric sensing. Thus, the external illumination provided by the light source 1341 may be particularly advantageous such that the display layer 1336 is not relied upon for illumination. It should be noted that in some embodiments the external light source 1341 may be collocated within the display layer, however, which may not be desirable as this may potentially reduce the emission area of the display 1323.

The light source 1341 may also decrease processing time for imaging the user's finger 1340, for example. As described above, the size and/or shape (e.g. rectangular) of each of the pin holes may determine a respective point spread function which in turn may determine resolution. For a desired resolution, the light source 1341 may provide increased SNR to thus reduce integration time, as will be appreciated by those skilled in the art.

A method aspect is directed to a method of making an electronic device. The method includes positioning a pin hole array mask layer 1350 above an optical image sensor 1331 and positioning a display layer 1336 above the pin hole array mask layer. The display layer 1336 includes spaced apart display pixels. The method also includes positioning a light source 1341 laterally adjacent the optical image sensor 1331 and capable of directing light into a user's finger 1340 when adjacent the optical image sensor.

The benefits of biometric data collected by a device as disclosed herein include convenient access to device features without the use of passwords. In other examples, user biometric data is collected for providing users with feedback about their health or fitness levels. The present disclosure further contemplates other uses for personal information data, including biometric data, that benefit the user of such a device.

Practicing the present invention requires that collecting, transferring, storing, or analyzing user data, including personal information, will comply with established privacy policies and practices. In particular, such entities should implement and consistently use privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining personal information data private and secure, including the use of data encryption and security methods that meets or exceeds industry or government standards. Personal information from users should not be shared or sold outside of legitimate and reasonable uses. Further, such collection should occur only after receiving the informed consent of the users. Additionally, such entities would take any needed steps for safeguarding and securing access to such personal information data and ensuring that others with access to the personal information data adhere to their privacy policies and procedures. Further, such entities can subject themselves to evaluation by third parties to certify their adherence to widely accepted privacy policies and practices.

The present disclosure also contemplates the selective blocking of access to, or use of, personal information data, including biometric data. Hardware and/or software elements disclosed herein can be configured to prevent or block access to such personal information data. Optionally allowing users to bypass biometric authentication steps by providing secure information such as passwords, personal identification numbers (PINS), touch gestures, or other authentication methods, alone or in combination, is well known to those of skill in the art. Users can further select to remove, disable, or restrict access to certain health-related applications collecting users' personal health or fitness data.

Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims. 

That which is claimed is:
 1. An electronic device comprising: an optical image sensor; a mask layer having an array of pin holes and at least one light opening therein; a display layer comprising a plurality of spaced apart light emitting diodes (LEDs) configured to provide illumination to the optical image sensor for sensing an object when adjacent the optical image sensor, the mask layer being disposed between the optical image sensor and the display layer; and at least one light source adjacent the optical image sensor and below the mask layer aligned with the at least one light opening, and configured to direct light into the object when adjacent the optical image sensor and also provide illumination to the optical image sensor for sensing the object when adjacent the optical image sensor.
 2. The electronic device of claim 1 wherein the at least one light source is laterally adjacent the optical image sensor.
 3. The electronic device of claim 1 further comprising a transparent cover layer above the display layer defining an object placement surface configured to receive an object adjacent thereto.
 4. The electronic device of claim 3 wherein the transparent cover layer defines a finger placement surface configured to receive a user's finger adjacent thereto.
 5. The electronic device of claim 3 wherein the at least one light source is adjacent the transparent cover layer so that light from the at least one light source is directed into the object when adjacent the transparent cover layer.
 6. The electronic device of claim 1 wherein the at least one light source comprises at least one of a visible light source, an infrared light source, and an ultraviolet light source.
 7. The electronic device of claim 1 wherein the optical image sensor, mask layer, and object placement surface are configured to define overlapping areas at the object placement surface, and spaced apart areas at the optical image sensor.
 8. The electronic device of claim 1 further comprising a flexible circuit substrate carrying the optical image sensor.
 9. The electronic device of claim 1 further comprising an optically transparent body between the optical image sensor and the mask layer.
 10. The electronic device of claim 1 further comprising an optically clear adhesive layer above the optical image sensor.
 11. The electronic device of claim 1 wherein the optical image sensor is configured to perform at least one of an authentication function, a spoof detection function, and a vital sign measurement function.
 12. An electronic device comprising: an optical image sensor; a pin hole array mask layer having at least one light opening therein; a display layer above the pin hole mask layer and comprising a plurality of spaced apart light emitting diodes (LEDs), the pin hole array mask layer being disposed between the optical image sensor and the display layer; and at least one light source laterally adjacent the optical image sensor below the pin hole array mask layer, and aligned with the at least one light opening to direct light into a user's finger when adjacent the optical image sensor.
 13. The electronic device of claim 12 further comprising a transparent cover layer above the display layer defining a finger placement surface configured to receive the user's finger adjacent thereto.
 14. A method of making an electronic device comprising: positioning a mask layer between an optical image sensor and a display layer, the mask layer having a plurality of pin holes and at least one light opening therein, the display layer being above the mask layer, and the display layer comprising a plurality of spaced apart light emitting diodes (LEDs) for providing illumination to the optical image sensor for sensing an object when adjacent the optical image sensor; and positioning at least one light source adjacent the optical image sensor and below the mask layer aligned with the at least one light opening, the at least one light source configured to direct light into the object when adjacent the optical image sensor and also provide illumination to the optical image sensor for sensing the object when adjacent the optical image sensor.
 15. The method of claim 14 wherein positioning the at least one light source comprises positioning the at least one light source laterally adjacent the optical image sensor.
 16. The method of claim 14 further comprising positioning a transparent cover layer above the display layer to define an object placement surface configured to receive an object adjacent thereto.
 17. The method of claim 16 wherein the transparent cover layer defines a finger placement surface configured to receive a user's finger adjacent thereto.
 18. The method of claim 16 wherein the at least one light source is positioned adjacent the transparent cover layer so that light from the at least one light source is directed into the object when adjacent the transparent cover layer. 